Table 1 Difference in maternal characteristics in the included and excluded groups
Maternal characteristics | Included n = 7824 | Excluded n = 1596 | Differences in mean or % | p-valuep |
|---|---|---|---|---|
Age (mean, SD) | 27.3 ± 0.1 | 27.3 ± 0.14 | 0 | 0.96 |
Education level (n, %) | ||||
 None | 1685 (21.5) | 424 (26.6) | + 5.1 | < 0.0001** |
 GCSE | 2475 (31.6) | 535 (33.5) | + 1.9 |  |
 A-level | 1235 (15.8) | 142 (8.9) | −6.9 |  |
 Higher than A-level | 1924 (24.6) | 337 (21.1) | −3.5 |  |
 Missing | 505 (6.4) | 158 (9.9) | + 3.5 |  |
IMD Level (n, %) | ||||
 Low deprivation | 2696 (34.5) | 500 (31.3) | −3.2 | 0.16 |
 High deprivation | 5125 (65.5) | 1096 (68.7) | + 3.2 |  |
 Missing | 3 (0.04) | 0 (0.0) | −0.04 |  |
Smoking status (n, %) | ||||
 Yes | 1375 (17.6) | 162 (10.2) | −7.4 | < 0.0001** |
 No | 6446 (82.4) | 1427 (89.4) | + 7.0 |  |
 Missing | 3 (0.04) | 7 (0.4) | + 0.36 |  |